Cold cathode counting tube circuits



1962 G. F. JEYNES 3,056,901

COLD CATHODE COUNTING TUBE CIRCUITS Filed April 21, 1959 2 Sheets-Sheet 1 2 P (*JUFFZY) v1 v3 RA? T GA K0 P 068 RB J R-C S CB1} [F.[JZT/WASZ) Q- g 6 (am) 5 (ma/w) INVENTOR GRAHAM FRANK JEYNES Oct. 2, 1962 G. F. JEYNES 3,056,901

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INVENTOR GRAHAM FRANK JEYNES BY W AGEN

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is alfifi 3,056,901 COLD CATHODE {IQUNTING TUBE CmCUlTS Graham Frank .Ieynes, treatharn Vale, England, assignor to North American Philips Company, Inc, New York, N .Y., a corporation of Delaware Filed Apr. 21, 1959, Ser. No. 807,787 4 Claims. (Cl. 31584.6)

This invention relates to devices for counting pulses comprising cold-cathode counting tubes. It relates more particularly to an improvement in the device for resetting the counting tubes to their initial positions.

Counting tubes of the foregoing type are described. for example, in British patent specification 712,171 and in their usual form comprise a gas filled tube having a plurality of cold cathodes spaced apart and associated with a common anode. Each cathode corresponds to a selected digit value to be indicated and is made to indicate by a glow discharge between it and the anode. In the counting procedure, the glow discharge travels from one cathodeanode gap to the next succeedig cathodeanode gap and to facilitate this transfer, as Well as to insure movement of the glow discharge in the desired direction, there are interposed between adjacent spaced cathodes two control electrodes each of which is adapted also to form a glow discharge in cooperation with the common anode.

Conventional devices for counting pulses comprise a plurality of counting tubes connected in cascade and separated by coupling circuits by which the output pulses of the counting tubes are amplified and transmitted to the subsequent counting tube. In such known devices the coupling circuit includes a discharge tube the control electrode of which is connected to the output electrode of the preceding counting tube and the anode of which is connected via a network to the input electrodes of the subsequent counting tube.

After a number of input pulses, a counting tube supplies a pulse to the output electrode. If the counting tube counts by the decimal system, it is formed with ten cathodes and the tenth input pulse brings about an output pulse. This output pulse is transmitted with amplification to the subsequent counting tube which then makes a counting step and reaches the condition corre sponding to the digit 1. After a subsequent pulse at the input electrodes, the preceding counting tube also reaches the condition corresponding to the digit 1. When a counting tube passes from condition 9 to condition 10 an output pulse occurs which is transmitted to the subsequent counting tube. If, however a counting tube passes from condition 10 to condition 1, any output pulse occurring must not be transmitted. In such counting tubes, the condition is reached again after the tenth input pulse occurs and when this condition is reached, at the same time an output pulse is given off to the subsequent counting tube.

Before starting on counting pulses, it is important for all the counting tubes to be in the O-condition so that each counting tube supplies an output pulse after the same number of input pulses.

It has been suggested to bring all the counting tubes to the O-condition by supplying a resetting pulse of suitable value and polarity to the output electrode of each counting tube. However, the practical realisation of this suggestion causes difficulty. During a resetting pulse, all the tubes pass to the O-condition, but as soon as the resetting pulse is switched off, a pulse is transmitted to the subsequent counting tube andthis pulsehas the same eifect as the output pulse normally transmitted during counting pulses. As a result thereof, after the resetting pulse, all the counting tubes are in the condition 1, except the first.

An object of the invention is to provide a device for resetting counting tubes connected in cascade by means of resetting pulses at the output electrodes of all the counting tubes so that, when the resetting pulse ceases, all the counting tubes remain in the O-condition.

The device according to the invention is characterized in that for resetting the counting tubes means are provided for supplying pulses to the cathodes of all the discharge tubes, the pulses having a value and a polarity such that the pulses are active through the discharge tube upon the output electrode of the preceding counting tube. This device aifords the advantage that, when the resetting pulse ceases, pulses having an effect similar to that of counting pulses are not transmitted to the subsequent counting tubes.

In one embodiment of a circuit arrangement accord ing to the invention, the cathodes of each discharge tube are connected through a diode to a point of fixed potential. These diodes are so connected that the performance of the discharge tube is not afiected when a counting pulse is transmitted.

In one preferred embodiment of a circuit arrangement according to the invention, the cathodes of the discharge tubes are connected together and coupled through a common diode to a point of fixed potential. This step results in a saving of the number of the diodes required.

In order that the invention may be readily carried into effect, it will now be described in detail, by way of example with reference to the accompanying drawing which:

FIG. 1 shows a portion of a conventional counting tube arrangement.

FIGS. 1 and 2 show embodiments of a circuit arrangement according to the invention.

FIG. 4 shows the circuit of the last counting tube of the arrangements shown in FIGS. 2 and 3.

The counting tubes V1, V3, V5 of FIG. 1 are of the type above described and have a gas filling and a central anode A encircled by ten cathodes K1 to K9 and K0. The cathodes K1 to K9 are connected together whereas cathode K0 is separately led to the exterior. Each two cathodes are separated by a first control electrode GA and a second control electrode GB, the first control electrodes and the second control electrodes being connected together. The anode A is connected through a resistor RP to a voltage source indicated by the terminal P. The output cathode K0 is connected through a resistor RK to a lead N and also to the control grid of a discharge tube V4 which is a conventional electron discharge tube such as the amplifier tube 55 shown in FIG. 2 of U.S. patent specification 2,860,286. The grid of this tube acquires through resistor RK a bias such that this tube is normally cut off. The cathodes K1 to K9 are connected to earth and the control electrodes GA and GB receive through lead G a positive bias. The anode of discharge tube V4 is connected through a resistor RL to a voltage source P. Also the anode of discharge tube V4 is connected via a blocking capacitor CA and a voltage divider RA, RC to the first control electrode GA of counting tube V5 and through a retarding network RB, CB to the second control electrode GB. Discharge tube V2 is similar to tube V4 and is connected to the counting tubes V1 and V3 in a similar manner as isdischarge tube V4 to the counting tubes V3 and V5.

This conventional circuit arrangement operates as follows.

An output pulse at the cathode K0 of counting tube V1, which may be the first in a chain of counting tubes, increases the voltage at the grid of discharge tube V2 so that this tube becomes conducting. The decrease in the anode voltage of this tube is transmitted via blocking capacitor CA and voltage divider RA, RC to the first control electrode of counting tube V3. If counting tube V3 is in the zero condition and hence with the discharge on the cathode K0, the discharge will be taken over by the first control electrode GA following this cathode. A short moment afterwards the decrease in voltage at the anode of discharge tube V2 is also transmitted via blocking capacitor CA and retarding network RB, CB to the second control electrode GB of counting tube V3. The discharge is now taken over by the second control electrode GB following the first control electrode. As a result of this discharge, the potential of the second control electrode GB increases and the potential difference with respect to the cathode K1 following the second control electrode reaches a value such that the discharge is taken over by cathode K1. The same action occurs in the transfer of the glow discharge from any given cathode K(N) the next succeeding cathode K(N +1). Any positive pulse at the cathode K of counting tube V1 thus has the effect that in counting tube V3 the glow discharge is transmitted from one cathode to the subsequent cathode. After 10 output pulses of counting tube V1, cathode K0 in counting tube V3 is struck by the discharge. The output pulse so produced is amplified by discharge tube V4 and supplied via voltage divider RA, RC to the first control electrode GA of counting tube V5 and via retarding network RB, CB to the second control electrode GB. During the time when the discharge in counting tube V3 takes place between the anode A and the output cathode K0, discharge tube V4 is conducting and the potential of the first control electrode GA and the second control electrode GB is equal to the bias which these electrodes receive through lead G. If, due to an output pulse at cathode K0 of counting tube V l, the discharge in counting tube V3 is taken over by the cathode K1, the grid voltage of discharge tube V4 decreases to the voltage of lead N. Discharge tube V4 is thus cut ofi and the anode voltage of this tube increases to the supply voltage of voltage source P. Thus set up at the control electrodes GA and GB of counting tube V5 are positive voltage pulses which however, do not affect the discharge in counting tube V5, since the polarity of these pulses is exactly opposite to that of the normal counting pulses. When the counting cycle starts, the dis charge in each of the counting tubes V1, V3, V5 mus-t be adjusted between the anode A and the output cathode K0. In known arrangements, for this adjustment of the couting tubes, a negative pulse is supplied to lead N. The cathodes K0 which are connected via resistor RK to the said lead acquire a high negative voltage with respect to the other cathodes, so that the discharge is taken over by cathode K0. Set up at the grids of the discharge tubes V2, V4, are now positive voltage pulses, the amplitude of which is substantially equal to that of the output pulses which normally occur in counting. These voltage pulses coincide with the negative pulse on lead N, so that the discharge tubes V2, V4 do not become conducting so long at the negative voltage pulse on lead N subsists. When the resetting pulse on lead N is switched oft, the discharge tubes become conducting, however, and the glow discharge in the counting tubes V3, V5 steps on to a subsequent cathode in the manner previously described.

In FIG. 2, discharge tube V2 is connected to the counting tubes V1 and V3 in a similar manner as in FIG. 1 and the performance of this circuit arrangement as regards the normal counting of pulses is similiar to that of the arrangement of FIG. 1. In the said arrangement, the counting tubes are reset to their zero positions in the following manner. A negative resetting pulse is supplied to lead S which is connected through blocking capacitors CD to the cathodes of all the discharge tubes. The diodes D connecting the cathodes of the discharge tubes to the earth wire E must be disregarded for the time being. In this connection it is to be noted that the blocking capacitors CD are not essential parts of a circuit arrangement according to the invention. The amplitude of the resetting pulse has been chosen to be greater than the voltage on l lead N. The discharge tubes, including the discharge tube V2 considered herein, become conducting and these tubes also convey grid current. As a result of this grid current, the grid voltage of each of the discharge tubes differs only slightly from the cathode voltage. The negative resetting pulse thus acts through the discharge tubes upon the output cathodes K0 of the counting tubes. The discharge in the counting tubes is taken over by the output cathodes K0 and the negative voltage of these cathodes is maintained due to the diode action of the discharge tubes. When the discharge tubes become conducting, the voltage at the anodes also decreases, due to which the counting tubes V3 can make a counting step in the manner previously described. As a result of the direct-current blocking between the control electrodes GA and GB and the anode of the preceding discharge tube, the voltage at these control electrodes gradually increases again due to the charging of blocking capacitor CA. When the counting tubes V3 make a counting step due to the preceding counting tube becoming conducting, the increase in voltage at the control electrodes GA and GB and the maintenance of the negative voltage at the output cathode K0 causes the discharge to return to the cathodes K0. After a short moment, the discharge in each counting tube is adjusted to the output cathode K0, whereupon the resetting pulse on lead S may be switched off. In this circuit arrangement, in contradistinction to the conventional type, the switching off of the resetting pulse has no particular effect, since the discharge tubes V2 remain conducting.

The diodes D have the task to reduce the detrimental influence exerted by the pulse source connected to lead S upon the normal performance of the discharge tube. During the counting of pulses, the diode D constitutes an effect short-circuit of this pulse source and the anode current of the discharge tube is passed unhindered. The diodes D are cut oil during a resetting pulse.

In FIG. 3, the cathodes of the discharge tubes V2, V4 are connected to the common lead S and through the diode D, the earth wire E. The counting tubes V1, V3, V5 are reset by the supply of negative pulses to the said lead S, so that the discharge in each counting tube is adjusted to the output cathode K0 in the manner previously described.

FIG. 4 shows in what manner the last counting tube of the counting tube arrangements shown in FIGS. 2 and 3 is reset. The cathode K0 of this last counting tube is connected to lead S, to which the resetting pulses are supplied, as previously described. When the resetting pulse ceases, the discharge also in this tube occurs between anode A and output cathode K0.

In the embodiment shown in FIGS. 2 and 3, the voltage of voltage source, P, may be for example from 300 to 350 volts positive with respect to the earth wire E. The positive bias of lead G may be, for example, 40 volts and the negative bias of lead N may be for example 12 volts, each voltage reckoned with respect to the earth wire E. The other components may have the following values:

Resistors RA, RB 56,000 ohms.

Resistor RC 82,000 ohms. Resistor RD 100,000 ohms. Resistor RK 120,000 ohms. Resistor RC 220,000 ohms. Resistor RP 800,000 ohms. Capacitor CA .0033 mmf. Capacitor CB .0015 mrnf. Capacitor CD .0033 mmf. Tubes V1, V3, V5 Mullard Z303 C. Tubes V2, V4 Mullard E88CC (each /2 section of dual triode) Diode D Type 0A202.

What is claimed is:

1. Electrical apparatus for counting pulses comprising a plurality of cold cathode counting tubes arranged in cascade each comprising first electrode means, a plurality of second electrode means spaced from said first electrode means and adapted to produce individual glow discharges between electrode pairs constituted by said first and second electrode means, one of said second electrode means including an output electrode, an input electrode system comprising a plurality of control electrodes for consecutively actuating said second electrode means, input circuit means for applying a control signal to said input electrode system thereby to cause a glow discharge to step from one of said electrode pairs to a next succeeding pair, an output electrode system comprising said output electrode for producing an output signal in response to the formation of a glow discharge at said output electrode, and circuit means interconnecting a first one of said counting tubes and a second counting tube thereby to apply said output signal to the input electrode system of said second counting tube, said circuit means comprising a discharge tube having a control electrode, a cathode and an anode, means connecting said control electrode to the output electrode system of said first counting tube, means connecting the anode to the input electrode system of said second counting tube, and means for resetting the glow discharge of said first counting tube to the position of said output electrode comprising means for applying a resetting pulse to said cathode.

2. Electrical apparatus for counting pulses comprising a plurality of cold cathode counting tubes arranged in cascade each comprising first electrode means, a plurality of second electrode means spaced from said first electrode means and adapted to produce individual glow discharges between electrode pairs constituted by said first and second electrode means, one of said second electrode means including an output electrode, an input electrode system comprising a plurality of control electrodes for consecutively actuating said second electrode means, input circuit means for applying a control signal to said input electrode system thereby to cause a glow discharge to step from one of said electrode pairs to a next succeeding pair, an output electrode system comprising said output electrode for producing an output signal in response to the formation of a glow discharge at said output electrode, and circuit means interconnecting a first one of said counting tubes and a second counting tube thereby to apply said output signal to the input electrode system of said second counting tube, said circuit means comprising a discharge tube having a control electrode, a cathode and an anode, means connecting said control electrode to the output electrode system of said first counting tube, means connecting the anode to the input electrode system of said second counting tube, and means for applying to said cathode a resetting pulse having an amplitude and polarity producing conduction through said discharge tube establishing said cathode and control electrode at substantially the same potential thereby applying said pulse to said output electrode and resetting the glow discharge of said first counting tube to the posiiton of said output electrode.

3. Electrical apparatus for counting pulses comprising a plurality of cold cathode counting tubes arranged in cascade each comprising first electrode means, a plurality of second electrode means spaced from said first electrode means and adapted to produce individual glow discharges between electrode pairs constituted by said first and second electrode means, one of said second electrode means including an output electrode, an input electrode system comprising a plurality of control electrodes for consecutively actuating said second electrode means, input circuit means for applying a control signal to said input electrode system thereby to cause a glow discharge to step from one of said electrode pairs to a next succeeding pair, an output electrode system comprising said output electrode for producing an output signal in response to the formation of a glow discharge at said output electrode, and circuit means interconnecting a first one of said counting tubes and a second counting tube thereby to apply said output signal to the input electrode system of said second counting tube, said circuit means comprising a discharge tube having a control electrode, a cathode and an anode, means connecting said control electrode to the output electrode system of said first counting tube, means connecting the anode to the input electrode system of said second counting tube, means for energizing said discharge tube comprising a circuit element at reference potential, diode means connecting said cathode to said circuit element in series conductive relationship, and means for resetting the glow discharge of said first counting tube to the position of said output electrode comprising means for applying a resetting pulse to said cathode.

4. Electrical apparatus for counting pulses comprising a plurality of cold cathode counting tubes arranged in cascade each comprising first electrode means, a plurality of second electrode means spaced from said first electrode means and adapted to produce individual glow discharges between electrode pairs constituted by said first and second electrode means, one of said second electrode means including an output electrode, an input electrode system comprising a plurality of control electrodes for consecutively actuating said second electrode means, input circuit means for applying a control signal to said input electrode system thereby to cause a glow discharge to step from one of said electrode pairs to a next succeeding pair, an output electrode system comprising said output electrode for producing an output signal in response to the formation of a glow discharge at said output electrode, and circuit means interconnecting a first one of said counting tubes and a second counting tube thereby to apply said output signal to the input electrode system of said second counting tube, said circuit means comprising a discharge tube having a control electrode, a cathode and an anode, means connecting said control electrode to the output electrode system of said first counting tube, means connecting the anode to the input electrode system of said second counting tube, means for connecting in common the cathodes of the discharge tubes interconnecting consecutive counting tubes, means for energizing said discharge tubes comprising a circuit element at reference potential, diode means connected in series conductive relationship between said common cathodes and said circuit element, and means for resetting the glow discharge of said counting tubes to the position of said output electrode comprising means for applying a resetting pulse to said cathodes.

References Cited in the file of this patent UNITED STATES PATENTS 2,860,286 Ost Nov. 11, 1958 

